Need an Updateable query

[Jerry]

I'm using Access 2003 on a Vista Premium Home OS. I have an Update query
that gives me the error "Operation must be an updatable query".

The Update quey is trying to update one field in a table based on the
results of another query that checks for entries within a date range.

The query is as follows:
UPDATE Error_Code_Master
INNER JOIN Last_Occurances ON Error_Code_Master.Error_Code =
Last_Occurances.Error_Code
SET Error_Code_Master.Status = "OB";

The query that checks the dates is as follows:
SELECT Error_Data.Error_Code, Max(Error_Data.Date) AS MaxOfDate,
Error_Code_Master.Status
FROM Error_Code_Master RIGHT JOIN Error_Data ON Error_Code_Master.Error_Code
= Error_Data.Error_Code
GROUP BY Error_Data.Error_Code, Error_Code_Master.Status
HAVING (((Max(Error_Data.Date))<[Prior to:]))
ORDER BY Error_Data.Error_Code;

Any idea what I'm doing wrong?

thanks